A 1-$\mu\hbox{W}$ 600- $\hbox{ppm}/^{\circ}\hbox{C}$ Current Reference Circuit Consisting of Subthreshold CMOS Circuits

Abstract

A low-power CMOS current reference circuit was developed using a 0.35-μm standard CMOS process technology. The circuit consists of MOSFET circuits operating in the subthreshold region and uses no resistors. It compensates for the temperature effect on mobility μ and threshold voltage V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> of MOSFETs and generates a reference current that is insensitive to temperature and supply voltage. Theoretical analyses and experimental results showed that the circuit generates a stable reference current of 100 nA. The temperature coefficient of the current was 520 ppm/°C at best and 600 ppm/°C on average in the range of 0°C-80°C. The line regulation was 0.2%/V in a supply voltage range of 1.8-3 V. The power dissipation was 1 μW, and the chip area was 0.015 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Our circuit would be suitable for use in subthreshold-operated power-aware large-scale integrations.